Of the large number of commercial synthetic insecticides available today, relatively few exhibit systemic activity, that is, the ability to be absorbed by the vascular system of the plant to be protected and to be translocated to the parts of the plant attacked by insects. Once ingested by the insect, the systemic insecticide acts as a strong stomach poison and thus provides efficient insect control. Moreover, not all commercial synthetic insecticides having systemic activity possess desirable broad spectrum activity against a wide variety of insects.
A major advantage inherent in the mode of action of a systemic insecticide and not shared by contact poisons is that beneficial insects which do not feed on the protected plants are not harmed by application of the systemic toxicant. In addition, systemic materials are generally not subject to loss of activity caused by weathering, e.g., heavy rain and strong sunlight, and, consequently, relatively few applications of the insecticide are required for long lasting insect control.
The compounds of this invention possess the major attributes of a systemic insecticide, viz., good systemic properties and high stomach toxicity, to an exceptional degree and also exhibit broad spectrum activity against a wide variety of insects. Nowhere in the prior art currently known to us is there any disclosure or suggestion of the discovery of the novel hydroxyarylalkyleneaminoaryl carbamate compounds or derivatives of the present invention which exhibit superior toxicity as insecticides, particularly superior systemic toxicity as aphicides. U.S. Pat. No. 3,012,068 discloses Schiff base carbamate esters prepared by (1) the reaction of an appropriate aldehyde compound with an appropriate amine compound, i.e., (a) a benzaldehyde compound with an aminophenol compound, or (b) a hydroxybenzaldehyde compound with an aniline compound to produce an intermediate Schiff base phenol and water followed by (2) the reaction of the intermediate Schiff base phenol with methyl isocyanate in the presence of a basic catalyst. However, U.S. Pat. No. 3,012,068 neither discloses, suggests nor exemplifies the hydroxyarylalkyleneaminoaryl carbamate compositions and derivatives of the present invention. In fact, the hydroxyarylalkyleneaminoaryl carbamate compositions and derivatives of the present invention are specifically excluded from the scope of U.S. Pat. No. 3,012,068 in that the aldehydes disclosed for reaction (a) above are restricted to no hydroxy substituents (column 2, lines 6 and 7). The hydroxyarylalkyleneaminoaryl carbamate compositions and derivatives of the present invention as exemplified by 4-(2-hydroxybenzylideneamino)-3,5-dimethylphenyl methylcarbamate unexpectedly exhibit superior systemic toxicity as aphicides in comparison with the Schiff base carbamate esters disclosed in U.S. Pat. No. 3,012,068.